Electrical coil assembly

ABSTRACT

An electrical coil assembly wherein two or more separate windings are formed in the same intermediate layer of a layerwound coil. A formed insulating board is provided for insulating and positioning the pair of conductors from each winding which are brought out toward the margin of the coil assembly. Additional layers of insulating material and other electrical windings are wound over the layer having two or more separate windings.

[451 June 6, 1972 [54] ELECTRICAL CO IL ASSEMBLY 7 3,518,596 6/1970 Connell.................................336/l92 [72] inventor: Henry Walsh,Jr.,Danville, 111.

Primary Examiner-E. A. Goldberg 731 Assignee 22 Filed:

General Electric Company Attorney-Frank L. Neuhauser, OscarB. Waddell, Joseph B. I 0c. 19 1970 Forman, John M. Stoudt, Ralph E. Krisher, Jr. and Radford M. Reams [Zl] Appl.No.: 81,930

ABSTRACT m m ry w ea. mm mm aro P d ma ek n m Zlca mm ib c m.m l m beu m. ..m en. 1mm i r mum n am .l n v mm m m Aww mm .2 2 "W 0/ ing and positioning the pair of conductors from each winding which are brought out toward the margin of the coil assem bly. Additional layers of insulating material and other electrical windings are wound over the layer havin separate windings.

References Cited UNITED STATES PATENTS g [W0 01' more Varley 4 Drawing Figures 1,723,261 8/1929 2,779,928 1/1957 Jeffrey...

Rechel 5 Claims,

PATENTEDJUH 51972 INVENTOR Henry f Atto fines Wah ' This invention relates to an electrical coil assembly for use in an electromagnetic inductive device such as a ballast transformer. More particularly, the inventionrelates to electrical coil assemblies wherein at least two separate windings or coils are formed in a single intermediate layer, and a pair of conductors from each winding are brought out toward the margin of the coil assembly.

Electrical coil assemblies generally used in transformers, such as ballast transformers for electrical discharge lamps, employ one or more windings which are either layer wound in successive layers, between which insulating layers are interposed, or are precision wound in successive layers without layer insulation. If the winding is to be utilized in a ballast circuit as a high voltage secondary winding, a'relatively large number of turns will be required and the winding will extend through a plurality of layers. Where a winding is to be utilized as a filament heating winding in a ballast transformer, only a limited number of turns occupying only a fraction of a layer may be required. In certain applications'one ballast transformer may be used in a circuit arrangement for energizing a plurality of electrical discharge lamps, each of which is provided with a pair of filaments. In a typical circuit arrangement, one electrode of each of two lamps may be energized at the same potential, such that the filaments at each of these electrodes maybe energized by the same filament heating winding. In such circuit arrangements the number of filament heating windings required will be one more than the number of lamps to be energized by the ballast, i.e., for two lamps three filaments, forthree lamps -four filaments, for four lampsfive filaments.

It has been customary to wind filament windings, which usually comprise a relatively few number of turns, in a side-byside relationship'in the outermost winding layer of an electrical coil assembly used in a ballast transformer. However, it has now been found desirable to provide electrical coil assemblies for ballast transformers wherein a greater number of filament heating windings are to be provided than the number that can be wound in the outermost layer of the electrical coil assembly. Such being the case, it has beenfound desirable to be able to provide at least two filament heating windings in a single conductor layer, other than outermost conductor layer, such that additional'layers of insulation and conductors may be wound thereover.

OBJECTS or THE INVENTION It is therefore a primary object of this invention toprovide a novel and improved electrical coil assembly wherein at least two single layer coils may be wound in the same layer of an electrical coil assembly, wherein that layer is not the outermost layer. I

A more specific object of the invention is to provide an improved electrical coil assembly having an improved conductor insulating and securing means for winding at least two single layer windings in the same layer, which layer is not the outermost layer of the electrical coil assembly.

SUMMARY OF THE INVENTION The foregoing objects are accomplished in accordance with this invention when in the preferred embodiment at least a pair of single layer windings are wound in a spaced apart relationship in a single layer over a layer of insulating material. A preformed insulating member orboard is positioned over the windings on the side of the coil assembly from which the start and finish conductors or leads of each of the windings are to be taken. The preformed insulating member or board is provided with a pair of notches for each winding. For each winding, the first notch is in axial alignment with the start or first end turn, and the second notch is in axial alignment with the finish or second end turn. The first and second notches for each winding are further arcuately spaced apart from each other by a central axially extending portion of the insulating member. The start and finish conductors of each of the windings are drawn through the notch and bent outward axially toward the adjacent margin of the coil assembly. The conductors in being drawn through and bent over the notches are thus located in a predetermined position. The preformed insulating board also provides insulation between the conductor or I lead of the coil located closer to the axial center of the coil assembly and the turns of the coil over which it extends. An insulating pad having conductive terminals secured thereto may be positioned on and secured to the preformed insulating board for making connections to the winding leads. A layer of insulation is thereafter wound over the single layer of separate single layer windings, the preformed insulating board, and the start and finish conductors or leads extending from the coils such that further windings may be wound thereover.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a completed electrical coil assembly constructed in accordance with this invention.

FIG. 2 is a perspective view of the coil assembly shown in FIG. 1 with portions broken away to show a pair of electrical coil windings with a preformed insulating board positioning and insulating the leads of the windings.

FIG. 3 is a top view of the electrical coil assembly shown in FIG. 1 with the layers of insulation underlaying and overlaying the outermost layer of conductor turns and the outermost layer of conductor turns removed.

FIG. 4 is a perspective view of the preformed insulating board.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, l have illustrated therein is an electrical coil assembly 10 having a rectangular precision wound multi-layer coil 12. This multilayer precision wound coil is not provided with layer insulation, nor-is it permanently formed over a spool. It is understood of course that this coil could also be layer wound with alternate insulation layers and conductor layers. As best seen in FIGS. 1 and 2, both the start conductor 14 and the finish conductor 16 are located at the top of one end of the coil. A layer of insulating material such as kraft paper 18 is wound over the outermost layer of the coil 12. As further shown in FIGS. 1 and 2 strips of insulating adhesive tape 20 and 22 are wound around the coil 12 and the insulating paper 18 to secure the coil 12 and the insulating paper 18 in their assembled position. A tape 24 is wound around the coil 12 and the insulating paper 18 to secure the start conductor 14. Similarly, a tape 26 is wound around the coil 12 and the insulating paper 18 to secure the finish conductor 16.

As is best seen in FIGS. 2 and 3 a pair of single layer multiturn coils 28 and 30 are wound in a spaced apart relationship over the insulating paper 18. The insulating paper 18 is prevented from unwrapping prior to the winding of coils 28 and 30 by two pieces of insulating tape 32. After the coils 28 and 30 are wound, a preformed insulating member or board 34 is positioned over the coils 28 and 30 and secured thereto by the tape 36 as shown in FIGS. 2 and 3.

Referring now to FIG. 4, it will be seen that the insulating board 34 is generally rectangular, with a pair of trapazoidal portions cut out of the longer side. The insulating board 34 is thus formed with wider end portions 38 and 40 and center section 42 of reduced width. The wider end portion 38 forms a pair of notches 44 and 46 with the narrower reduced width central portion 42. Similarly, the wider end portion 40 forms a pair of notches 48 and 50 with the reduced width central portion 42. It will be noted that the notches 44 and 46 are spaced apart in the longitudinal direction, axially with respect to the coil assembly, by a distance equal to the axial winding transverse of the coil 28. Similarly, the notches 48 and 50 are spaced apart in a longitudinal direction by a distance equal to the axial winding traverse of the coil 30.

Again with reference to FIG. 2, a first lead or conductor 52 of coil 28 is bent through the notch 46 to extend in the longitudinal direction of the insulating board 34, or axially with respect to the coil assembly, to the adjacent margin of the coil assembly. Similarly, the second-lead 54 of the coil 28 is bent through the notch 44 to extend in a longitudinal direction over the insulating board 34 to the adjacent margin of the coil. In a similar fashion at the opposite end of the coil assembly the first lead 56 of the coil 30 is bent through the notch 50 and the second lead 58 is bent through the notch 48.

As is best seen in FIG. 3, the leads S2 and 54 extending from coil28 are secured in place on the insulating board34 by an adhesive insulating tape 60. It will be noted that the preformed insulating board 34, and more particularly the wider endportion 38 provides insulation under the first lead 52 and second lead 54 of the coil 28. In the case of second lead 54, the wider end portion 38 provides insulation from the turns of coil 28.

An alternate method of terminating the leads 56 and 58 of coil 30 is shown in-FIG. 3. A piece of insulating material or board 62 has secured thereto, such as by-staking or riveting, a pair of electrical conductive terminals 64 and 66. The insulating board 62 is secured over thepreformed insulating board 34 by a piece of insulating adhesive tape 68. The first lead 56 of coil 30 is wrapped around and soldered to terminal 64, while the second lead 58 is wrapped around and soldered to the terminal66.

To complete the coil assembly, additional layers of insulating material 70as best seen in FIG. 2 are wound over the assembly as shown in FIG. 3. In accordance with the practice of the prior art, a plurality of separate windings are wound in a single layer .over the insulating material 70. Three such separate windings or coils 72, 74 and 76 are shown in FIG. 2.

After winding the coils 72, 74 and 76 a strip of tape 78, as shown in FIG. 1, is placed over the coils. Leads 79 and 80extending from coil72, leads 82 and 84 extending from coil 74 and leads 86 and 88 extending from coil 76 are bent radially outward from the center of the coil assembly adjacent the tape 78. Layers of insulating material 90 are thereafter wound over the coils 72, 74 and 76, terminating adjacent opposite edges of the tape 78 as seen in FIG. 1. The insulating material 90 is secured in place over the winding 72, 74 and 76 by adhesive insulating tapes 92 and 94.

Thus, using the electrical coil construction of this invention it is possible for instance to provide five filament windings in a coil assembly wherein it would have been impossible to provide the five filament windings in-a single outer layer. In accordance with this invention, two of the filament windings 28 and 30 are wound in the same intermediate layer with their leads extending in an axial direction toward the nearest margin of the .coil assembly. After placing sheets of insulating material thereover, three additional filament windings 72, 74 and 76 are wound in the outermost layer of the coil. Wherein it is not necessary to bring the leads of the coils in the outermost layer of the coil assembly to the margins of the coil, in order to wind additional layers of insulation and coils thereover, a greater number of coils may be wound in the outermost layer.

While in accordance with the patent statutes a preferred embodiment of the invention is shown with two coils 28 and 30 wound in a single intermediate layer, a modification of the invention would provide for winding a larger number of coils in the intermediate layer. For instance, a second reduction in the width of the reduced width central portion 42 of the insulating board 34 might be provided, such that four more notches might be provided in the insulating board. These four additional notches would be used to position and secure the leads of two additional coils wound in the same layer as the coils 28 and 30. These notches would be located closer to the center of the insulating board 34, and the leads extending from the two additional coils would be spaced apart from each other and located between and spaced from the leads 52 and 54 of coil 28 and the leads 56 and 58 of coil 30.

ile as shown in FIG. 4 a pair of trapazoidal notches are cut out on each of the longitudinal sides of the preformed insulating board 34, the notches could of course be of other shapes such as rectangular or stepped rectangular. A stepped rectangular notch would provide a groove for retaining the conductor adjacent the reduced width central portion, 42 of the preformed insulating board 34. The coil leads of the coils 28 and 30 have been referred to as both first and second and start and finish leads. Whether one or the other of the two leads of each coil is the start or finish lead depends on the winding traverse, i.e. the coil is wound right to left or left to right. Since the direction of winding is not important to this invention, either lead of the coils 28 and 30 can be referred to as the start lead, and the other as the finish le'ad.

While in accordance with the patent statutes the preferred embodiment of the invention has been shown and described, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from this invention in its broader aspects and, therefore, it is intended that the appended claims cover all such changes and modifications as fall within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electrical coil assembly wherein at least a pair of single layer windings are formed side-by-side in a single intermediate conductor layer of the electrical coil assembly, said intermediate layer overlaying an insulating layer and underlaying subsequent layers of windings and insulation, each of said at least a pair of single layer windings comprising at least one turn and having a start conductor and afinish conductor, a preformed insulating member positioned over said at least a pair of single layer windings, said preformed insulating member being formed with a plurality of notches, said notches being positioned in said insulating member such that one of said notches is aligned with each of said start conductors and each of said finish conductors of each of said at least a pair of single layer windings, each of said start and finish conductors being positioned in said one of said notches and bent over said insulating member to be retained in a predetermined position and to extend axially toward the adjacent end of the coil assembly.

2. The electrical coil assembly as set forth in claim 1 wherein said preformed insulating member is formed with a reduced width center section and wider end portions at opposite ends of the center section, said plurality of notches being formed between said wider end portions and said reduced width center section.

3. The electrical coil assembly as set forth in claim 2 wherein said preformed insulating member is generally rectangular and said reduced width center section and said wider end portions of said preformed insulating member are formed by removing a pair of generally trapazoidal portions from opposite sides of said insulating member.

4. The electrical coil assembly as set forth in claim 1 wherein each of said start and finish conductors are bent over said insulating member and overlays said insulating member such that the innermost one of said start and finish conductors of each of said at least a pair of single layer windings is insulated from the turns of its winding by said preformed insulating member.

5. The electrical coil assembly as set forth in claim 1 wherein means are provided to secure said start and finish conductors of each of said at least a pair of single layer windings and said preformed insulating member such that subsequent layers of windings and insulation may be wound over said at least a pair of single layer windings and said preformed insulating member. 

1. An electrical coil assembly wherein at least a pair of single layer windings are formed side-by-side in a single intermediate conductor layer of the electrical coil assembly, said intermediate layer overlaying an insulating layer and underlaying subsequent layers of windings and insulation, each of said at least a pair of single layer windings comprising at least one turn and having a start conductor and a finish conductor, a preformed insulating member positioned over said at least a pair of single layer windings, said preformed insulating member being formed with a plurality of notches, said notches being positioned in said insulating member such that one of said notches is aligned with each of said start conductors and each of said finish conductors of each of said at least a pair of single layer windings, each of said start and finish conductors being positioned in said one of said notches and bent over said insulating member to be retained in a predetermined position and to extend axially toward the adjacent end of the coil assembly.
 2. The electrical coil assembly as set forth in claim 1 wherein said preformed insulating member is formed with a reduced width center section and wider end portions at opposite ends of the center section, said plurality of notches being formed between said wider end portions and said reduced width center section.
 3. The electrical coil assembly as set forth in claim 2 wherein said preformed insulating member is generally rectangular and said reduced width center section and said wider end portions of said preformed insulating member are formed by removing a pair of generally trapazoidal portions from opposite sides of said insulating member.
 4. The electrical coil assembly as set forth in claim 1 wherein each of said start and finish conductors are bent over said insulating member and overlays said insulating member such that the innermost one of said start and finish conductors of each of said at least a pair of single layer windings is insulated from the turns of its winding by said preformed insulating member.
 5. The electrical coil assembly as set forth in claim 1 wherein means are provided to secure said start and finish conductors of each of said at least a pair of single layer windings and said preformed insulating member such that subsequent layers of windings and insulation may be wound over said at least a pair of single layer windings and said preformed insulating member. 